Small Engines (Lawn Mowers, etc.): kohler 17.5 hp commander, john deere l110, voltage rectifier

Question
its 5 yrs old in a john deere L110 tractor, wife put 2cycle in the tank,,not a biggy it just smoked a bit, half way through the tank the batterie died(five years old fair enough) first the headlights got real bright( for a second ) then went out then a few minutes later the tractor died. the battery was dead. so i put a new battery in, replaced both headlight bulbs and it would just crank, if i sprayed carb cleaner she would lite for a second, so new plug and fuel filter, took apart and cleaned carb. and same problem. cranked and smelled plug and i dont smell fuel but its definetly getting to the bowl and filling it..what is the solenoid on bottom of the bowl? one red wire comming out of it..family-3khxs.4902gb
                       displ-490
                       m#cv491s
                       spec 27509
                       s#3304202471

Answer
Almost seems you are experiencing two problems at the same time. First off most  mowers once started no long relies on the battery to run. With the headlights getting bright all of a sudden tells me the regulator that regulates the charging to the battery failed, and may be bad. Or the voltage rectifier. Also check all fuses. Make sure all safety's are operating correctly, some times when a mower dies during mowing we forget to shut everything back off while restarting, taking it out of reverse, disengaging the blades, and such. The solenoid on the bottom of the float bowl is a fuel shut of, it operates from the key, key on solenoid pulls back a plunger letting fuel in, key off it becomes de-energized allowing the plunger to move forward closing off any fuel from further entering the bowl. This could be one of your problems. Touch the side of the solenoid while someone turns the key off, and on, do you feel it click in and out? Without being energized it's position is off (No Fuel) check your fuses..........Tom